I'm really sorry, but there is not an easy solution we can provide you. I may suggest you either reduce the 15-minute value or make the changes yourself using the wpdiscuz_is_comment_editable hook. 

More info here: https://wpdiscuz.com/docs/codex/filters/wpdiscuz_is_comment_editable/ 

i use Allow comment editing option for my users and i set the edit time for them on 15 minutes and this option work very well

but there is an issue for me , in my website I have to confirm the comments before publishing for many reasons

the issue is here that
when a user edit his comment before confirm everthing is ok but when i publish comments if a user still have time for editing he can edit his comment after my confirmation for that comment and i do not want this because maybe he write somthing which Be against the rules of my website and after that i can not confirm it again because i did it once before

i want a code which makes i can not confirm the comments which did not past their 15 min and only when i can do this which they past this time

or give me a code that Specifies this comments with a color or icon that tells me 15 minutes time has over and you can confirm this comment now